This invention relates to railroad couplers, and more particularly to improvements to a coupler head for assembling a knuckle thrower therein and/or a retainer to engage with an end portion of a knuckle thrower trunnion for preventing withdrawal of the trunnion from an assembled position in a coupler head.
Couplers for railway vehicles comprise an assembly of parts including a coupler head with spaced-apart pivot lugs at the knuckle side to receive a pivot pin for pivotally attaching a knuckle thereto. A cavity in the coupler head includes a floor wall section with a pivot pin hole to receive a trunnion of a knuckle thrower. The thrower has two oppositely extending legs used to pivot the knuckle in response to tilting movement of a lock. The thrower is an irregularly shaped element usually made as a casting or a forging. In standard A.A.R. coupler heads, Type E and Type F, a projection called a thrower retaining shelf extends from the back wall of the coupler head in the cavity to entrap the thrower against unwanted dislodgement of its trunnion from the thrower hole in the bottom of the coupler head. However, when coupler assemblies are handled during shipment, the thrower can be dislodged from its normally-seated location in the coupler head. Moreover, when the coupler is rotated, as is the practice with certain designs of rotary couplers, the thrower trunnion may fall out of the thrower hole. In other instances, rotary movement of a coupler assembly during installation on a railway car dislodges the thrower from its operative position. The dislodgement of the thrower is usually apparent because of abnormal locking and unlocking operations of the coupler. The coupler must be disassembled for access to the thrower. This is time-consuming, inconvenient and a very undesirable condition to contend with at remote sites.
The thrower retaining shelf may, therefore, fail to provide its intended function when a coupler is rotated. The shelf is obscurely situated as a projection from the back wall in the coupler head adjacent the horn line. The coupler head is a casting requiring loose core pieces to form the thrower retaining shelf. This adds to the cost of the manufacture of the coupler head, particularly when a shelf is angled or deflected from its required site because of wear of the core box equipment or an improperly set core piece. In an E-type coupler, for example, the bottom surface of the shelf is situated about 11/8 inches above the floor wall containing the thrower retaining hole. A sharp corner can occur in the back wall of the coupler head between the floor and the thrower retaining shelf, thus creating a weak, low-strength area in the coupler head which cannot be readily detected. The relatively thin wall section of the thrower retaining shelf projects in a cantilevered fashion to varying dimensions of about 11/4 inches and greater. An improperly formed shelf may occur due to an unusually cold liquid metal that prevents proper flow of the molten metal during the casting process.
In standard A.A.R. couplers, the existence of the thrower retaining shelf creates an obstruction that necessitates tipping of the thrower in order to align and permit dropping of the trunnion into its support hole in the bottom of the coupler head. Fitting of the trunnion may be required. Assembling of the thrower in the coupler head is usually a tedious undertaking because of the obstruction caused by the thrower retaining shelf. So far as presently known, the thrower retaining shelf has always been considered essential and part of an A.A.R. standard coupler.